Poly alkanol esters of alkylthio-alkanoic acids

ABSTRACT

Alkyl esters derived from alkylthioalkanoic acids and alkane polyols are stabilizers of organic material normally subject to thermal and oxidative deterioration. They are prepared by conventional esterification techniques. Typical embodiments are pentearythritol tetrakis (3-n-dodecylthiopropionate) and ethylene bis (3-n-didecylthiopropionate). The esters are used in conjunction with phenolic antioxidants to effectively stabilize organic materials from the deliterious effects of heat and oxygen.

United States Patent 1 Dexter et al.

1 Sept. 11, 1973 POLY ALKANOL ESTERS OF ALKYLTHIO-ALKANOIC ACIDS [73]Assignee: Ciba-Geigy Corporation, Ardsley,

22 Filed: Oct. 12, 1971 21 Appl.No.: 188,436

[52] U.S. Cl 260/48] R, 44/70, 99/163,

252/407, 260/4535, 260/3985 [51] Int. Cl. ..C07c 149/20 [58] Field ofSearch 260/481 R [56] References Cited UNITED STATES PATENTS 2,601,0636/1952 Smith et al 260/481 R FOREIGN PATENTS OR APPLICATIONS 2,028,24012/1970 Germany 260/48] R OTHER PUBLICATIONS Nagakubo et al. CA. 571398lf Primary Examiner-Lorraine A. Wcinberger Assistant Examiner-JohnF. Terapane Att0rneyl(arl F. Jorda and Nestor W. Shust [57] ABSTRACTAlkyl esters derived from alkylthioalkanoic acids and alkane polyols arestabilizers of organic material normally subject to thermal andoxidative deterioration. They are prepared by conventionalesterification techniques. Typical embodiments are pentearythritoltetrakis (3-n-dodecy1thiopropionate) and ethylene bis(3-n-didecylthiopropionate). The esters are used in conjunction withphenolic antioxidants to effectively stabilize organic materials fromthe deliterious effects of heat and oxygen.

3 Claims, No Drawings POLY ALKANOL ESTERS OF ALKYLTHIO-ALKANOIC ACIDSThe present invention pertains to alkyl esters of alkylthioalkanoicacids and to compositions which are stabilized by these esters and tovarious novel uses of these esters.

In particular, this invention pertains to compounds of the formula:

wherein R is an alkyl group of from one to 18 carbon atoms,

n has a value of from 2 to 4; and

z is an aliphatic hydrocarbon of the formula;

y 2u+2-n in which y has a value of from 2 to l8 when n is 2 and a valueof from 3 to 6 when n is greater than 2, the value ofy in all casesbeing equal to or greater than that of n.

Illustrative examples of the alkyl groups of from one to l8 carbon atomswhich are represented by R are methyl, ethyl, propyl, pentyl, heptyl,decyl, dodecyl, octadecyl and the like. Alkyl groups of higher molecularweight can also be used such as those containing up to about carbonatoms. R groups containing from 12 to 18 carbon atoms are mostpreferred. Embraced within these groups are both the straight andbranched chain alkyl groups.

The alkylthioalkanoic acids esters of alkane polyols of the presentinvention have as their characteristic property the ability to vastlyimprove the effect of numerous other compounds which are used asstabilizers for organic material normally subject to thermal andoxidative deterioration. Thus while the compounds of the presentinvention may be considered as stabilizers in their own right, theirproperties are such that they would be more conventionally classified assynergists in that when combined with known stabilizers, they exhibitthe ability to increase stabilization to a degree for exceeding thatwhich would be expected from the additive properties of the individualcomponents.

Organic materials which, being normally subject to deterioration, areoften stabilized by the addition of various stabilizing compounds andwhich therefore are suitable for the further addition of compounds ofthe present invention include for example synthetic organic polymericsubstances such as vinyl resins formed by the polymerization of vinylhalides or from the copolymerization of vinyl halides with unsaturatedpolymerizable compounds, e.g. vinyl ester, a,fl unsaturated esters,a,B-unsaturated acids, a,B-unsaturated ketones or aldehydes andunsaturated hydrocarbons such as butadiene and styrene; poly-a-olefinssuch as polypropylene, polyethylene, polybutylene, polyisoprene and thelike, including copolymers of a-olefins; polyurethanes such as areprepared from polyols and organic polyisocyanates; polyamides such aspoly(hexamethylene adipamide); polyesters such as poly(methyleneterephthalates); polycarbonates; polyacetals; polystyrene; poly(ethyleneoxide); copolymers such as those found by the copolymerization ofacrylonitrile, butadiene and/or styrene; as well as physical mixtures ofthe above such as high impact polystyrene containing copolymers ofbutadiene and styrene; formaldehyde-alkyd finishes and the like.

Other materials so stabilized include lubricating oils such as those ofthe aliphatic ester type e.g., di-hexyl azelate,di-(2-ethylhexyl)azelate, di-(3,5,5,-tri-methylhexyl)glutarate,di(3,5,S-trimethylpentyl)-glutarate, di-(2)ethylhexyl)pimelate,di-(2-ethylhexyl)-adipate, diisoamyl adipate, triamyl tricarballate,pentaerythritol tetracaproate, dipropylene glycol dipelargonate, l,5-pentanediol di-(Z-ethylhexanoate), and the like; fats and oils of animaland vegatable origin e.g. linseed oil, menhaden oil, cod liver oil,castor oil, olive oil, rapeseed oil, coconut oil, palm oil, corn oil,sesame oil, peanut oil, cotton seed oil, butter, fat, lard, beef tallowand the like; saturated and unsaturated hydrocarbons such as forexample, both natural and synthetic gasolines, jet fuels, diesel oils,mineral oils, fuel oils, drying oils, waxes and resins.

The compounds of this invention exhibit their novel properties whencombined with a wide variety of stabilizers some of which arecommercially available and some of which are the subject of Patents.

Typical of the phenolic antioxidants whose stabilizing properties areimproved by the addition of compounds of the present invention, are thefollowing:

1. Phenolic compounds having the general formula urea- Q( z)w wherein Qis A is (CR(COOR") H2)wQ COOR" R is hydrogen or lower alkyl R is loweralkyl R" is alkyl group having from six to 24 carbon atoms w is aninteger from 1 to 4.

Illustrative examples of the compounds shown above are T5 ooocmnndi-n'-octadecyl(3-t-butyl-4-hydroxy-5-methylbenzyl)- malonatedi-n-octadecyl ot(3-t-butyl-4-hydroxy-5-methylbenzyl)malonate which isdisclosed in the Netherlands Patent No. 6,711,199

di-n-octadecyl-a,a-bis-(3-t-butyl-4-hydroxy-5- methylbenzyl)malonatewhich is disclosed in the Netherland Patent No. 6,803,498

2. Phenolic compounds having the general formula Illustrative examplesof the compounds shown above are 2,6-di-t-butylphenol2,4,6-tri-t-butylphenol 2,6-dimethylphenol 2-methyl-4,o-di-t-butylphenol3. Phenolic compounds having the formula A-C I-I Q2,2-methyIene-bis(6-t-butyl-4-methylphenol)2,2'-methylene-bis(6-butyl-4-ethylphenol)4,4-butyIidene-bis(2,6-di-t-butylphenol)4,4-(2-butylidene)-bis(Z-t-butyI-S-methylphenol) 2,2'-methyIene-bis[6-(l-methylcyclohexyl)-4- methylphenol and the like.

4. Phenolic compounds having the formula ROQ Illustrative examples ofsuch compounds are 2,5-di-t-butylhydroquinone 2,6-di-t-butylhydroquinone2,5-di-t-butyI-4-hydroxyanisole 5. Phenolic compounds having the formulaQSQ Illustrative examples of such compounds are4,4'-thiobis-(2-t-butyI-5-methylphenol)4,4-thiobis-(2-t-butyI-6-methylphenol)2,2-thiobis-(6-butyI-4-methylphenol) 6. Phenolic comp ounds having theformula Illustrative examples of such compounds are octadecyl-( 3 ,5-dimethyl-4-hydroxybenzylthio )acetatedodecyl-(3,5-di-t-butyl-4-hydroxybenzylthio)propionate 7 Phen9Iiccompounds having the formula wherein T is hydrogen R or Q as definedabove.

Illustrative examples of such compounds arel,1,3-tris(3,5-dimethyI-4-hydroxyphenyl)-propane l, I ,3-tris(-t-butyl-4-hydroxy-2- methylphenyl)butane 1,1 ,5,5-tetrakis-( 3'-t-butyl-4'-hydroxy-6-methylphenyl)-n-pentane 8. Phenolic compoundshaving the formula wherein B, B and B are hydrogen or Q, provided thatwhen E and 18 are Q then B is hydrogen and when B is Q then B and B arehydrogen.

Illustrative examples of such compounds are I,4-di(3,5-di-t-butyl-4-hydroxybenzyl)-2,3,5,6-tetramethylbenzeneI,3,5-tri( 3 ,5-di-t-butyI-4-hydroxybenzyl )-2,4,6-

trimethylbenzene 9. Phenolic compounds having the formula Z is NHQ, S-Dor O-Q D is alkyl group having from six to I2 carbon atoms or (C,,,I'I)SR" Illustrative examples of such compounds are2,4-bis(n-octylthio)-6-(3,5-di-t-butyl-4-hydroxyanilino )-I,3,5-triazine6-(4-hydroxy-3-methyI-5-t-butylanilino-2,4-bis-(noctylthio)-I,3,5-triazine6-(hydroxy-3,S-dimethylanilino)-2,4-bis-(n-octylthio)-1,3,5-triazine6-(4-hydroxy-3,S-di-t-butylanilino)-2,4-bis-(noctylthioethyIthio)-l,3,5-triazine 6-(4-hydroxy-3,S-di-t-butylanilino)-4-(4-hydroxy- 3,S-di-t-butylphenoxy )-2-(n-octylthio)- l ,3 ,5-

triazine2,4-bis(4-hydroxy-3,S-di-t-butylanilino)-6-(noctylthio)-1,3,5-triazine.The above phenolic triazine stabilizers are more fully described in U.S.Pat. No. 3,255,191.

10. Phenolic compounds having the formula Illustrative examples of suchcompounds are 2,4-bis-(3,5-di-t-butyl-4-hydroxyphenoxy)-6-(noctyIthio)-I,3,5-triazine 2,4,6-tris-(4-hydroxy-3,5-di-t-butylphenoxy)- l ,3,5-

triazine6-(4-hydroxy-3,5-di-t-butyIphen0xy)-2,4-bis-(noctylthioethylthio)- l ,3,S-triazine 6-(4-hydroxy-3-methylphenoxy)-2,4-bis-(n-octylthio)-l,3,5-triazine6-(4-hydroxy-3-t-buylphenoxy)-2,4-bis-(noctyIthioethylthio)-l,3,5-triazine 6-(4-hydroxy-3-methyl-5-t-butylphenoxy)-2,4-bis-(n-octylthio)-l ,3,5-triazine2,4-bis-(4-hydroxy-3-methyI-S-t-butyIphenoxy)-6- (n-octylthio)-l,3,5-triazine 2,4,6-tris-(4-hydroxy-3-methyl-5-t-butylphenoxy)-1,3,5-triazine6-(4-hydroxy-3,5-cli-t-butylphenoxy)-2,4-bis-(noctyIthiopropylthio)-l,3,5-triazine6-(4-hydroxy-3,5-di-t-butylphenoxy)-2,4-bis-(ndodecylthioethylthio l,3,5-triazine 2,4-bis-(4-hydroxy-3,5-di-t-butyIphenoxy)-6- butyIthio-l,3 ,S-triazine2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(noctadecylthio)-l,3,5-triazine2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(ndodecylthio)-l,3,5-triazine2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(noctyIthiopropyIthio)-l,3,S-triazine2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(noctylthioethylthi0)- l ,3,S-triazine2,4-bis-(4-hydroxy-3,5-di-t-butylphenoxy)-6-(ndodecylthioethylthio)-l,3,5-triazine.The above phenolic triazine stabilizers are more fully described in US.Pat. No. 3,255,191.

11. Phenolic compounds having the formula [QC,H -CO0C.H R

wherein p is an integer from 1 to 4 and R' is a tetravalent radicalselected from aliphatic hydrocarbons having from one to 30 carbon atomsaliphatic mono and dithioethers having from one to 30 carbon atomsaliphatic mono and diethers having fromone to 30 carbon atoms.

1 has a value of from 0 to 6. Illustrative examples of such compoundsare Sub-class I n-Octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionaten-Octadecyl 3,5-di-t-butyl-4-hydroxyphenylacetate n-Octadecyl3,15-di-t-butyl-4-hydroxybenzoate n-I-Iexyl3,5-di-t-butyl-4-hydroxybenzoate n-Dodecyl3,5-di-t-butyl-4-hydroxybenzoate Neo-dodecyl3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate Dodecyl2-(3,5-di-t-butyl-4-hydroxyphenyl)propionate Ethylor-(4-hydroxy-3,S-di-t-butylphenyl)-isobutyrate Octadecyla-(4-hydroxy-3,5-di-t-butylphenyl)- isobutyrate Octadecyla-(4-hydroxy-3,5 -di-t-butylphenyl propionate Sub-class II2-(n-octylthio)ethyl 3,5-di-t-butyl-4- hydroxybenzoate2-(n-octylthio)ethyl 3,5-di-t-butyl-4-hydroxyphenylacetate2-(n-octadecylthio)ethyl 3,5-di-t-butyl-4-hydroxyphenylacetate2-(n-octadecylthio)ethyl 3,5-di-t-butyl-4-hydroxy benzoate2-(2-hydroxyethylthio)ethyl 3,5-di-t-butyl-4- hydroxybenzoate2,2-Thiodiethanol bis(3,5-di-t-butyl-4-hydroxyphenyl)acetate Diethylglycol bis-[3,5-di-t-butyl-4-hydroxyphenyl)- propionate]2-(n-octadecylthio)ethyl hydroxyphenyl)propionate2,2-Thiodiethanol-bis-3-(3,5-di-t-butyl-4-hydroxyph enyl)propionateStearamido N,N-bis-[ethylene 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] 3-(3,5-di-t-butyl-4- n-ButyliminoN,N-bis-[ethylene 3-(3,5-di-t-butyl-4- hydroxyphenyl)propionate] 2-(2-stearoyloxyethylthio)ethyl hydroxybenzoate 2-(2-hydroxyethylthio)ethyl7-(3-methyl-5-t-butyl-4- hydroxyphenyl)heptanoate2-(2-stearoyloxyethylthio )ethyl7-(3-methyl-5-tbutyl-4-hydroxyphenyl)heptanoate 3,5-di-t-butyl-4-Sub-class Ill 1,2-pr0pylene glycol bis-l3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] Ethylene glycolbis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] Neopentylglycolbis-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] Ethylene glycolbis-(3,5-di-t-butyl-4-hydroxyphenylacetate) Glycerinel-n-octadecanoate-2,3-bis-( 3 ,S-di-t-butyl- 4-hydroxyphenylacetatePentaerythritol tetrakis [3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]l, l l -trimethylol-tris-3-(3,5-di-t-butyl-4hydroxyphenyl)propionateSorbitol hexa-[3-(3,5-di-t-butyl-4-hydroxyphenyl)- propionate]1,2,3-butanetriol tris-[3-(3,5di-t-butyl-4-hydroxyphenyl)propionate]Z-hydroxyethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoate2-stearoyloxyethyl 7-(3-methyl-5-t-butyl-4-hydroxyphenyl)heptanoatel,6-n-hexanediol-bis[( 3 ',5 -di-t-butyl-4-hydroxyphenyl)propionate] Theabove phenolic ester stabilizers of sub-classes I, II and Ill are morefully described in U.S. Pat. No. 3,33- 0,859, Ser. No. 354,464, filedMar. 24, 1964 and Ser. No. 359,460, filed Apr. 13, 1964, respectively.

12. Phenolic compounds having the formula Illustrative examples of suchcompounds are Dioctadecyl 3,5-di-t-butyl-4-hydroxybenzylphosphonateDi-n-octadecyl 3-t-butyl-4-hydroxy-5-methylbenzylphosphonateDi-n-octadecyl l-(3,5-di-t-butyl-4-hydroxyphenyl)- ethanephosphonateDi-n-tetradecyl 3,5-di-t-butyl-4-hydroxybenzylphosphonate Di-n-hexadecyl3,5-di-t-butyl-4-hydroxybenzylphosphonate Didocosyl-3,5-di-t-butyl-4-hydroxybenzylphosphonate Di-n-octadecyl 3,5-di-t-butyl-4-hydroxybenzyl- Other materials often added to suchorganic materials, depending upon the substrate, include pour-pointdepressants, corrosion and rust inhibitors, metal deactivators,demulsifiers, antifoam agents, carbon black, accelerators, plasticizers,color stabilizers, heat stabilizers, dyes, pigments and the like.

The alkyl alkylthioalkanoic acid esters of the present invention arepreferably used in a concentration of from 0.005 percent to about 10percentby weight of the total composition together with one or more ofthe above phenolic antioxidants, one or more ultraviolet light absorbersand/or one or more of the above phosphite compounds. These areparticularly useful in synthetic organic polymeric substances such aspolypropylene, polyethylene, polystyrene and the like to protect suchsubstances from deterioration both during use and during processing suchas milling polypropylene or blow molding polyethylene. The compounds ofthe present invention exhibit superior compatability in diversesubstances with little or no odor formation.

They are particularly useful in organic polymeric fibers because oftheir extraction resistance and low volatility.

These compounds may be incorporated or blended into polymericcompositions by the conventional methods utilized for blending suchmaterials into resins and plastics. Typical of such methods that can besuitably employed include milling on heated rolls, deposition fromsolvents, and dry blending.

, The compounds of formula 1 may be prepared by reacting an alkylmercaptan of the formula R-S-l-l 11 wherein R is as defined previously,with methyl acrylate as described by Stevens et al, J. Am. Chem. Soc.73, Vol. 50 (1951). The monoester thus obtained is reacted with a alkanepolyol of the formula wherein Z is as defined previously, via a standardtransesterification reaction. The transesterification reaction involvesa treatment of the polyol with up to a 15 percent excess, preferablyfrom to percent excess, over stoicheometric amount of the ester. Thisreaction is catalyzed with a hydride or lower alkoxide of an alkalinemetal such as lithium hydride, lithium methoxide or sodium methoxide.These catalysts are employed in an amount from about 0.01 to about 0.30mole equivalents per mole of polyol. The reaction is conducted atelevated temperatures and under reduced pressure, the lower alkanolwhich is formed being removed by distilation.

The alkane polyols of formula 3 are well known and most are commerciallyavailable. The polyols will thus consist of the straight orbranched-chain hydrocarbon residue of the formula ll 21l+2-n and anumber of hydroxy groups equal to n. When n is two, i.e., the polyol isa diol, this hydrocarbon residue will have from two to 18 carbon atomsand preferably from three to nine carbon atoms. When n is greater thantwo; i.e., the polyol is a triol, or tetrol, the hydrocarbon residuewill have from three to seven carbon atoms. In all cases the number ofhydroxy groups and the resulting number of alkylthioalkanoyloxy groups(as designated by n) will be equal to or less than the number of carbonatoms (y) in the hydrocarbon residue; i.e., since each carbon atom ofthe hydrocarbon residue can bear only one hydroxy group y is equal to orgreater than n.

The following examples, presented for illustration and not limitation,will further serve to typify the nature of the present invention. Inthese examples, parts are by weight unless otherwise indicated.

EXAMPLE 1 Methyl 3-n-dodecylthiopropionate Methyl acrylate, 86.1 parts,was added to a cold mixture of n-dodecyl mercaptan, 123 parts, andsodium methylate, 0.5 parts, over a 50 minute interval. The temperatureof the reaction was kept at 2530C by means of an ice-bath. After all thereactants were combined, the reaction mixture was stirred at the ambienttemperature for about 17 hours. After this time about 1 part offiltercel was added and the resulting slurry filtered through a sinteredglass funnel. The product was purified by vacuum distillation. There wasobtained 125.8 parts of the above-named product having boiling point152-153.5C, 0.3-0.4 mm which gave the following analysis:

Analysis for C H SO Calculated: C, 66.61; H, 11.18; S, 11.11.

Found: C, 66.86; H, 11.30; S, 10.92.

By essentially following the procedure of this example, but substitutingfor n-dodecyl mercaptan an equivalent amount of the following alkylmercaptans:

a. ethylmercaptan b. n-hexylmercaptan c. n-octylmercaptan d.n-decylmercaptan e. n-octadecylmercaptan there is respectively obtainedmethyl 3-ethylthiopropionate methyl 3-n-hexylthiopropionate methyl3-n-octylthiopropionate methyl 3-n-decylthiopropionate methyl3-n-octadecylthiopropionate EXAMPLE 2 Ethylenebis(3-n-dodecylthiopropionate) a. A mixture consisting of 31.74 parts ofmethyl 3-n-dodecylthiopropionate and 3.10 parts of ethylene glycol wasstirred and 0.14 parts of sodium methylate added. The reaction mixturewas heated for about 6.5 hours at l00i5C in a nitrogen atmosphere. Aftercooling to room temperature, the reaction mixture was dissolved in 1:1benzene-heptane and passed through a bed of alumina. After removingimpurities in the early fractions, the pure product was obtained as awhite solid having melting point 50-2.

Analysis for C H S 0 Calculated: C, 66.84 H, 10.86; S, 11.15

Found: C, 67.13; H, 10.66; S, 11.22

b. By essentially following the procedure of this example, butsubstituting for the reactants, i.e., ethylene glycol and methyl3-n-dodecylthiopropionate an equivalent amount of the followingreactants:

1. 1,2-propylene glycol methyl 3-ethylthiopropionate 2. 1,4-butane diolmethyl 3-n-hexylthiopropionate 3. neopentyl glycol methyl3-n-octylthiopropionate 4. 1,5-pentanediol methyl3-n-decylthiopropionate 5. 1,6-hexandiol methyl3-n-octadecylthiopropionate 6. 1,12-dodecanediol methyl3-n-dodecylthiopropionate 7. 1,2-octadecane methyl3-ndodecylthiopropionate there is respectively obtained 1,2-propylenebis(3-ethylthiopropionate) 1,4-butane diol bis(3-n-hexylthiopropionate),

. neopentyl glycol bis(3-n-octylthiopropionate) 1,5-pentanediolbis(3-n-decylthiopropionate) 1,6-hexanediolbis(3-n-octadecylthiopropionate) 1,12-dodecanediolbis(3-n-dodecylthiopropionate) 7. 1,2-octadecanediolbis(3-n-dodecylthiopropionate) EXAMPLE 3 tris( 3-n-dodecylthiopropion-EXAMPLE 4 Pentaerythritol tetrakis( 3-n-dodecy1thiopropionate) Byemploying the procedure of the previous example and substitutingpentaerythritol for ethylene glycol, there is obtained the above namedproduct as a white solid melting at 479. Analysis for C H S O iCalculated: C, 67.18; H, 10.75; S, 11.03

Found: C, 66.99; H, 10.55; S, 11.03

In a similar manner by substituting an equivalent amount ofmethyl-3-n-octadecylthiopropionate for methyl-3-n-dodecylthiopropionatethere is obtained pentaerythritol tetrakis(3-n-octadecylthiopropionate).

EXAMPLE Unstabilized polypropylene powder (Hercules Profax 6501) wasthoroughly blended with 0.3 percent by weight of the variousalkylthioesters of this invention and 0.1 percent by weight variousphenolic antioxidants. The blended materials were then milled on atwo-roll mill at 182C for 10 minutes, after which time the stabilizedpolypropylene was sheeted from the mill and allowed to cool.

The milled polypropylene sheets were then cut into pieces and pressedfor 7 minutes on an hydraulic press at 218C on a hydraulic press at 500psi and then transferred to a cold press at 500 psi. Samples of theresulting 25 mil sheet were tested for resistance to accelerated agingin a forced draft oven at C. The results are set out in Table 1 below:

TABLE 1 Oven Aging at 150C Additive(s) Hours to Failure 0.3%pentaerythritol tetrakis(B-n-dodecylthiopropionate) 0.1% pentaerythritoltetrakis l3-(3,5-di-t-butyl-4-hydroxyphenyl)propion- The above dataclearly indicates the significant increase in the stabilization ofpolypropylene upon the addition of the alkyl esters of alkylthioalkanoicacids of the present invention.

EXAMPLE 6 A water-white, refined (U.S.P. grade) mineral oil (Esso PRIMOLD) is stabilized and tested under the following test conditions.

A sample of the mineral oil 10 g) containing 0.3 percent by weight ofdi-n-octadecyl 3,5-di-ti-butyl-4- hydroxybenzyl phosphonate and 0.1percent of ethylene bis(n-dodecylthiopropionate) is placed in a Slightype oxidation flask filled with oxygen at room temperature (25C) andatmospheric pressure. Thereafter, the flash is sealed to form a systemhaving a mercury manometer which measures the pressure changes as oxygenis absorbed by the sample of the flask. The sample is then heated at150C until the manometer registers a decrease of 300 mm HG pressurewithin the flasks with reference to the maximum pressure obtained at150C. Results of this test show the increase oxidation resistance forthe sample containing the stabilizer.

EXAMPLE 7 High impact polystyrene resin containing elastomer (i.e,butadiene-styrene) is stabilized against loss of elongation propertiesby incorporation of 0.3 percent by weight ofdi-n-octadecyl(3-t-butyl-4-hydroxy-5- methylbenzylmalonate and 0.1percent pentaerythritol 'tetrakis (3-n-dodecylthiopropionate). Under thetest conditions described below, the stabilized resin retains a higherpercentage of its original elongation properties, whereas theunstabilized resin retains less elongation properties. A substantialimprovement in stability is also noted when only 0.05 percent of thestabilizer is employed.

The unstabilized resin is dissolved in chloroform and the stabilizerthen added, after which the mixture is cast on a glass plate and thesolvent evaporated to yield a uniform film which, upon drying, isremoved and cut up, and then pressed for 7 minutes at a temperature of163C and a pressure of 2,000 pounds per square inch into a sheet ofuniform thickness (25 mil). The sheets are then cut into stripsapproximately 4 X 0.5 inches. A portion of these strips is thenmeasureed for length of elongation in the instron Tensile (lnstronEngineering Corporation, Quincy, Mass). The remaining portion of thestrips is aged in a forced draft oven for 6 weeks at 75C and thereaftertested for elongation. The stabilized polystyrene resin has retainedmuch better its elongation property than the unstabilized resin.

Similar results are obtained when an equivalent amount of the followingstabilizer combinations are used in place of the above mentionedstabilizer combinations.

a. 0.1 percent by weight of l,l2-dodecanediolbis(3-n-dodecylthiopropionate 0.3 percent of 4,-4-butylidene-bis(2,6-di-t-butylphenol) b. 0.1 percent by weight of1,2-octadecanediol bis(3-n-dodecylthiopropionate 0.3 percent of 2,-4-bis(n-octylthio)-6-(3,5-di-t-butyl-4-hydroxyaniline)-1 ,3,5-triazinec. 0.1 percent by weight of 1,1 ,l-trimethylolpropanetris(3-n-dodecylthiopropionate) 0.3 percent of2,4-bis(3,5-di-t-butyl-hydroxyphenoxy-6-(n-octylthio) 1 ,2 ,3-triazineEXAMPLE 8 A quantity of SBR emulsion containing 100 g of rubber (500 mlof 20 percent SBR obtained from Texas U.S., Synpol 1500) previouslystored under nitrogen, is placed in a beaker and stirred vigorously. ThepH of the emulsion is adjusted to 10.5 with a 0.5N NaOH solution.

To the emulsion is added 50 ml of 25% NaCl solution. A 6% NaCl solutionadjusted with hydrochloric acid to a pH 1.5 is added in a thin streamwith vigorous stirring. When pH 6.5 is reached, the rubber begins tocoagulate and the addition is slowed down in order to maintain uniformagitation. The addition of the acidic 6% NaCl solution is terminatedwhen a pH 3.5 is reached. The coagulated crumb-rubber slurry at pH 3.5is stirred for one-half hour.

The coagulated rubber is isolated by filtration through cheese cloth,and rinsed with distilled water. After three subsequent washings withfresh distilled water, the coagulated rubber is dried, first at 25 mm Hgand finally to constant weight under high vacuum (1 mm) at 40-45C.

The dried rubber (25 g) is heated under nitrogen at 125C in a Brabendermixer and to this is added with mixing 1.25 g (0.5 percent of1,3,5-tri(3,5-di-t-butyl-4- hydroxybenzyl)2,4,6-trimethylbenzene and 0.1percent pentaerythritol tetrakis (3-n-octadecylthiopropionate). Thecomposition is mixed for minutes after which it is cooled andcompression molded at 125C into 5 inc X 5 inch X 0.025 inch plaques.

The plaques are placed on aluminum sheets and heated in a circulatingair oven at 100C for up to 96 hours. The viscosity of a 0.5 percenttoluene solution of aged and unaged rubber samples are determined at25C. Stabilizer effectiveness is judged by the percent retention ofspecific viscosity, color formation and gel content after oven aging.The stabilized rubber has better viscosity, color retention, and lessgel content than the rubber which is unstabilized after oven aging.

Similar results are obtained when n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate and neopentyl glycoltris(3-n-octylthiopropionate) is used in place of the above mentionedstabilizers in the rubber composition.

EXAMPLE 9 A composition is prepared comprising linear polyethylene and0.05 percent by weight of pentaerythritol tetrakis[3,(3,5-di-t-butyl-4-hydroxyphenyl)propionate] and 0.01 percent byweight of pentaerythritol tetrakis (3-n-dodecylthiopropionate). Thecomposition is injected molded into tensile bars which are placed in acirculating air oven at C. in contrast to those molded from unstabilizedlinear polyethylene, tensile bars molded from the instant compositionretained its tensile strength for substantially longer period EXAMPLE l0Cyclohexene, freshly distilled is stabilized by the addition thereto of0.05 percent by weight of 2,2- methylene-bis(6-t-butyl-4-methylphenol)and 0.01 percent by weight of 1,6-hexanediolbis(3-n-octadecylthiopropionate). The effectiveness of this stabilizerin cyclohexene is tested by the ASTM D 525-55 oxidation test. Theunstabilized cyclohexene fails in shorter time as compared to thestabilized cyclohexene.

EXAMPLE 1 l wherein n has a value of from 3 to 4; Z is an aliphatichydrocarbon of the formula:

u 2v+2n in which y has a value of from 3 to 6, the value of y beingequal to or greater than the value of n; and R is an alkyl group of from12 to 18 carbon atoms.

2. The compound of claim 1 which is 1,1 ,1- trimethylolethane bis(3-n-dodecylthiopropionate).

3. The compound of claim 1 which is pentaerythritoltetrakis(3-n-dodecylthiopropionate).

2. The compound of claim 1 which is 1,1,1-trimethylolethanebis(3-n-dodecylthiopropionate).
 3. The compound of claim 1 which ispentaerythritol tetrakis(3-n-dodecylthiopropionate).